C7 - Geologic and Ground Water Considerations

Question 1

figure 7-1 sa assignment na explanation

Answer 1

Storing, treating, or utilizing agricultural wastes and
nutrients at or below the ground surface has the potential to contaminate ground water

Question 2

covers all natural and processed soil and rock materials

Answer 2

geologic material or earth material

Question 3

Common examples of this property include mineral composition, grain size, consistency, color, hardness
(strength), weathering condition, porosity, permeability, and unit weight.

Answer 3

material properties

Question 4

refers to the orientation and deformation
characteristics, such as faults and joints.

Answer 4

Geologic structure

Question 5

is formed primarily in limestone terrain
and characterized by solutionally widened joints,
sinkholes, and caves.

Answer 5

Karst
topography

Question 6

include
discontinuities that are distinct breaks or abrupt
changes in the mass.

Answer 6

mass properties

Question 7

include fractures of
all types that develop sometime after a soil or rock
mass has formed.

Answer 7

Structural discontinuities

Question 8

common example of
a stratigraphic discontinuity

Answer 8

soil/bedrock interface

Question 9

All water beneath the surface of the Earth is called
___

Answer 9

underground water, or subsurface water

Question 10

Underground water occurs in two primary zones: an upper zone of aeration called the ___

Answer 10

vadose or unsaturated zone, and a
lower zone of saturation called the phreatic or saturated zone.

Question 11

contains both air and
water in the voids

Answer 11

vadose zone

Question 12

where all
interconnected voids are filled with water

Answer 12

saturated zone

Question 13

the only underground water available
for wells and springs

Answer 13

ground water

Question 14

Water in this zone
is available for transpiration by plants or direct evaporation.

Answer 14

vadose zone

Question 15

Water in this zone cannot move back up to the soil-water zone by capillary action.

Answer 15

intermediate zone

Question 16

This zone occurs in fine to medium
grained soils and in rocks with fractures less than 1/8
inch wide.

Answer 16

saturated zone

Question 17

Water in the___ is under less
than atmospheric pressure.

Answer 17

capillary fringe

Question 18

is a geologic unit capable of storing and
conveying usable amounts of ground water to wells orsprings

Answer 18

aquifers

Question 19

include sand and gravel alluvial
deposits on flood plains of perennial streams; glacial
outwash; coarse-grained, highly porous, or weakly
cemented sedimentary rocks (some sandstones and
conglomerates); and karst topography

Answer 19

Productive aquifers

Question 20

Some unconfined aquifers result in flowing artesian
wells. This occurs when the water table locally rises
above the ground surface. ____ is the primary
control on most flowing wells in major valley bottoms.

Answer 20

Topography

Question 21

is overlain by a confining layer of
lower permeability

Answer 21

confined aquifer

Question 22

well in a confined aquifer that has higher than atmospheric
pressure is called an __.

Answer 22

artesian well

Question 23

is the level to which ground water
rises in a tightly cased well penetrating a confined
aquifer

Answer 23

potentiometric
surface

Question 24

are typically remote from any
given well location.

Answer 24

Recharge areas

Question 25

is a local zone of unconfined ground water occurring at some level above the regional water table.

Answer 25

perched aquifer

Question 26

is defined as the ratio of the volume of voids to the total volume of a soil or rock mass, expressed as a percentage.

Answer 26

porosity

Question 27

refers to openings formed at the same time the material was formed or deposited.

Answer 27

primary porosity

Question 28

refers to openings formed after initial deposition or formation of a material. Processes that create secondary porosity include physical weathering (freeze-thaw, wetting and drying, heating and cooling), chemical or biological action, and other stresses that produce fractures and joints.

Answer 28

secondary porosity

Question 29

is the ratio of the volume of water that an unconfined aquifer (soil or rock) releases by gravity drainage to the volume of the soil or rock mass.

Answer 29

specific yield

Question 30

engineering geology considerations in planning

Answer 30

corrosivity location of water table depth to rock stability for embankment and excavated cut slopes excavability seismic stability dispersion permeability puncturability settlement potential shrink/swell topography availability and suitability of borrow material Presence of abandoned wells and other relics of past use

Question 31

are those in which the clay fraction is or may become deflocculated or disaggregated

Answer 31

dispersed soils

Question 32

refers to rate at which water flows through a material.

Answer 32

Permeability or hydraulic conductivity

Question 33

may allow the time needed for transformation and plant uptake of nutrients while soils with high permeability may leach contaminants

Answer 33

Soils with lower permeability

Question 34

is the ability of foundation materials to puncture a flexible membrane liner or steel tank.

Answer 34

Puncturability

Question 35

Angular rock particles greater than 3 inches in diameter in contact with a tank may cause __

Answer 35

denting or puncturing.

Question 36

Angular particles greater than 0.5 inch can be __.

Answer 36

a puncture hazard to plastic and synthetic rubber membranes

Question 37

Monolithic structures are designed to behave as a structural unit

Answer 37

Monolithic structures

Question 38

A foundation is susceptible to differential settlement if underlain by zones, lenses, or beds of widely different soil types with boundaries that change abruptly either laterally or vertically.

Answer 38

Abrupt, contrasting soil boundaries

Question 39

Layers or zones greater than 1 foot thick consisting of soft clays and silts, peat and organic-rich soil (OL and OH in the Unified System), and loose sands may settle excessively when loaded by an embankment or concrete structure.

Answer 39

Compressible soil

Question 40

Structures located in areas of active or abandoned underground mining or areas that have a high rate of ground water withdrawal can have problems resulting from settlement of the material.

Answer 40

Weak foundations

Question 41

Differential settlement of embankments may occur on abutment slopes steeper than 1 horizontal to 1 vertical. Adequate compaction is difficult to achieve on steep slopes. Settlement cracks may occur in the fill in the area where the base of a steep abutment joins the flood plain.

Answer 41

Steep abutments

Question 42

A foundation may settle if underlain by normally consolidated soil materials over a highly irregular, shallow bedrock surface or other uneven, unyielding material. As a rule, consider a foundation problematic if, in the foundation area, the difference between maximum and minimum thicknesses of the overlying compressible soil above an uneven rock surface divided by the maximum observed soil thickness is greater than 25 percent. This is expressed as "Problem foundation" when [100 (max. depth – min. depth/max.depth)]>25%

Answer 42

Uneven rock surface

Question 43

This soil is common especially in the western continental States. It has low density and low water content and formed in windblown silts and fine sands and rapidly deposited alluvial fans. This soil may undergo large, sudden settlement when it becomes saturated after loading by a structure built on it.

Answer 43

Collapsible soi

Question 44

Soil containing montmorillonite clay may undergo substantial changes in volume when ___

Answer 44

saturated

Question 45

may serve as aquifer recharge areas, and valley bottoms, marshes, and lowlands as ground water discharge areas.

Answer 45

uplands

Question 46

is formed on limestone, gypsum, or similar rocks by dissolution and is characterized by sinkholes, caves, and underground drainage.

Answer 46

Karst topography

Question 47

must meet gradation, plasticity, and permeability requirements for its intended use and be in sufficient quantity to build the component

Answer 47

borrow

Question 48

increases the opportunity for attenuation of contaminants because of its cation exchange capacity and its affect of reducing permeability.

Answer 48

Increased clay content

Question 49

hold a negative charge that gives them the capacity to interchange cations in solution

Answer 49

Clay particles

Question 50

has a very low permeability

Answer 50

clay

Question 51

refers to the vertical distance through which a contaminant must pass to reach the top of an aquifer.

Answer 51

depth

Question 52

The greater the ____between the source of the contamination and a well, spring, or other ground water supply, the greater the time of travel will be.

Answer 52

horizontal distance

Question 53

The greater the __, the greater opportunity for attenuation of contaminants.

Answer 53

travel time

Question 54

moves primarily from topographically higher recharge areas down gradient to withdrawal areas at lower elevations

Answer 54

Unconfined ground water

Question 55

is a material property that is determined by laboratory analysis, but is also commonly determined as a mass property through field testing

Answer 55

permeability

Question 56

a mass property of an aquifer that is determined through field testing, such as pump tests or slug tests. It is commonly known as permeability and is the rate of flow (L/t) of water through an aquifer

Answer 56

Hydraulic conductivity

Question 57

is the energy of a water mass produced mainly by difference in elevation, velocity, and pressure, expressed in units of length or pressure

Answer 57

Hydraulic head

Question 58

is the change in hydraulic head per unit distance of flow in a given direction and is expressed in units of length (elevation) per length (distance).

Answer 58

Hydraulic gradient

Question 59

is a function of the hydraulic gradient.

Answer 59

Ground water velocity

Question 60

is the study of the occurrence, movement, and quality of underground water.

Answer 60

Hydrogeology